As polyimide type positive photosensitive resin compositions, many have been reported wherein a quinonediazido compound is added to a polyamic acid or to a polyamic acid ester or polyimide having an acidic group in a side chain. However, a polyamic acid has a problem such that it is soluble so much in an alkali developer that film reduction at the time of the development is substantial, and it is necessary to use it by an addition of an amine or the like (U.S. Pat. No. 4,880,722). On the other hand, a polyimide (JP-A-3-115461) or polyamic acid ester (JP-A-64-60630) having an acidic group in a side chain is excellent in the developability, etc., but even after curing, acidic groups tend to remain in the polymer, whereby the final cured film was likely to have a high water absorption or its alkaline resistance was likely to substantially decrease. Further, with a positive photosensitive resin employing a resin mixture of a polyamic acid and a polyamic acid ester having an acidic group has a leaving component (Journal of Applied. Polymer Science, Vol. 51, P. 1971–1978), curing at a higher temperature is required to convert the polyamic acid ester to a polyimide, and film reduction by the curing tends to be substantial.
In recent years, use of photosensitive insulating films represented by photosensitive polyimide resins has been expanded not only to the semiconductor field but also to the display field. Accordingly, an excellent resolution free from film reduction or swelling in the formation of fine patterns, adhesion during the development, dimensional stability of the patterns in high temperature curing, etc. are now required, which have not been required for the conventional photosensitive polyimide resins. Among them, JP-A-2001-228609 has reported a positive photosensitive polyimide resin excellent in adhesion and developability, which comprises an alkali-soluble polyimide, a polyamic acid and an o-quinonediazido compound, but depending upon the combination of the polyimide and the polyamic acid, there has been a case where whitening of the film or the water absorption of the final cured film tends to be problematic.
Thus, the conventional positive photosensitive polyimide resins have had excellent properties respectively, but on the other hand, it has been difficult to develop a material which has both the lithographic properties and the properties for the final cured film and which provides patterns having high dimensional stability with little film reduction or swelling.
The present invention has been made in view of the above-described circumstances, and it is intended to provide a positive photosensitive resin composition which is free from film reduction, swelling or peeling at the time of the development with an aqueous alkaline solution and which provides patterns having high dimensional stability after curing, and of which the final cured film has a low water absorption and excellent alkaline resistance.